Can't find record in replication slaves

I have 2 slave servers in my replication system. Here are the steps how I setup the system

step 1:
Setup master(m1) -> slave(s1) replication after server initialization, after that I run data import on m1 using mysql < data.sql. Everything is ok, no error message in mysqld.log

step 2:
backup data on m1 (there is no activity on m1)
mariabackup --backup --extra-lsndir=/data/backup_3306 --compress --host=127.0.0.1 --port=3306 --user=backup --password=changme --compress-threads=16 --parallel=16 --stream=xbstream --tmpdir=/tmp/backup_3306 --target-dir=/data/backup_3306 > /data/backup.xbs

copy data to s2
scp .....

decompress data
mbstream -x < /data/local-backup/backup.xbs -C /data/restore
mariabackup --decompress --parallel=16 --target-dir=/data/restore

copy-back
mariabackup --defaults-file=/etc/my.cnf --copy-back --target-dir=/data/restore

fix permission issues
...

start mysql service
setup replication
start replication

Make m1 as slave with log_slave_update to Mysql 5.6 server. After a while, I can see the following error messages on both s1 and s2.

2017-09-28 13:52:26 140519051532032 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:26 140519051937536 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:26 140519051667200 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:26 140519051261696 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:26 140519051667200 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:29 140519051261696 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:29 140519051261696 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:29 140519051532032 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:30 140519051396864 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:30 140519051396864 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:30 140519051532032 [ERROR] mysqld: Can't find record in 't1'
2017-09-28 13:52:30 140519051802368 [ERROR] mysqld: Can't find record in 't1'

So could you please investigate what the problem is? Thanks.